2018 Prepared by: SATPALDA. (Dept. of Photogrammetry ) PROJECT ASSESSMENT REPORT FOR SITAMARHI PROJECT This is a project assessment report for a recent assignment successfully executed at SATPALDA Geospatial Services. It has been drafted with the assistance of the internal project manager of the photogrammetry division at SATPALDA. This report collectively demonstrate the methodology adopted, all technical aspects, output analysis and finally what we achieved in this project.
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PROJJEECCTT AASSSSEE SSSMMEENNTT RREEPPOORRTT … Terrain Model (DTM) Creation Digital Terrain Model (DTM) is a digital representation of a landscape. This is a combination of lines
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report for a recent assignment successfully executed at SATPALDA Geospatial Services. It has been drafted with the assistance of the internal project manager of the photogrammetry division at SATPALDA. This report collectively demonstrate the methodology adopted, all technical aspects, output analysis and finally what we achieved in this project.
About the organization
SATPALDA, an ISO 9001:2008 company is a privately owned organization and a leading provider of satellite imagery and geospatial services to the user community. Established in 2002, SATPALDA has successfully completed wide range of photogrammetric and remote sensing projects. Our cost effective solutions are catered to broad spectrum of government and private users. The USP of SATPALDA‘s services is the unique blend of experience and cost effectiveness. Presently, SATPALDA is actively engaged with the customers spreading over South-East Asia, Africa and Europe.
Our approach to geospatial solutions is to align with the business needs of clients, to design solutions that integrate commercially available imagery and GIS data themes to assist in decision making, data interrogation, data publishing and dissemination.
Services
Orthorectification
Aerial Triangulation
Terrain Modelling (DTM)
3D Modelling
LIDAR
Topographic Mapping
DGPS Survey
Land cover mapping
Specialized Process (Pan-Sharpening, Landsat ETTM+Gap-
WorldView-2 satellite sensor from DigitalGlobe provides 8-band multispectral imagery. It was launched on October 8, 2009 from Vandenberg Air Force Base on a Delta II rocket to become DigitalGlobe’s third satellite in orbit, joining WorldView-1 which was launched in 2007 and QuickBird which was launched in 2001. It takes a new photograph of any place on Earth every 1.1 days. The overall objective was to meet the growing commercial demand for high-resolution satellite imagery.
Launch Information: Date : October 8, 2009
Launch Vehicle : Delta 7920 (9 strap-ons)
Launch Site : Vandenberg Air Force Base,
California
Imagery acquisition
GCP collection
Aerial Triangulation
Aerial Triangulation approval by client
Digitization
Quality control of vector data
Contour generation
Quality Check (contour based)
Generate raster DTM
Quality Check of DTM
Data Delivered
Client's Approval
Orbit: Altitude : 770 km
Type : Sun synchronous 10:30 am
descending node
Period : 100 min
(View of WorldView-2 satellite. Image Courtesy: DigitalGlobe.)
Sensor Bands: Panchromatic: 450 – 800 nm
8 Multispectral:
Coastal: 400 – 450 nm Red: 630 -690 nm
Blue: 450 – 510 nm Red Edge: 705 – 745 nm
Green: 510 – 580 nm Near-IR1: 770 – 895 nm
Yellow: 585 – 625 nm Near-IR2: 860 – 1040 nm
Sensor Resolution: Panchromatic: 0.46 m GSD at nadir, 0.52 m GSD at 20° off nadir
Multispectral: 1.85 m GSD at nadir, 2.07 m GSD at 20° off nadir
Swath Width: 16.4 km at nadir
Revisit Frequency: 1.1 days at 1 m GSD or less
(40°N Latitude)
Geolocation Accuracy (CE90): Demonstrated <3.5m CE90 without ground control
Capacity: 1 million square km per day
GCP Collection (DGPS Survey)
Ground control points are large marked targets on the ground, spaced strategically throughout
the area of interest. When used correctly, ground control points greatly improve the global
accuracy of the image. They help ensure that the latitude and longitude of any point on our
image corresponds accurately with actual GPS coordinates. This is important in situations where
precision mapping and true global accuracy are needed.
Differential Global Positioning Systems (DGPS) are enhancements to the Global
Positioning System (GPSs) which provide improved location accuracy, in the range of
operations of each system, from the 15-meter nominal GPS accuracy to about 1cm in case of
the best implementations. The system has three major components: space, earth control, and
end user.
Basic Definitions
Base station: Base station receives signals from the satellite and create correction factor.
These corrections are further sent via radio to rovers.
Rover: A Rower is a survey tool used to receive signals from the satellite and a base station
to calculate grade.
PDOP: Position Dilution of Precision (PDOP) is the measure of geometrical strength of GPS
satellite configuration. As the PDOP value increases both the horizontal and vertical precision
• Place the Base station at a known point (make sure without the known point we cannot place the base station) *The base station should be leveled and centering accurately
2 • Measure the slant height with tap and start the receiver of the
base station.
3
• Check the number of satellite and PDOP value in a controller display. Now in a controller type, we enter the name of the point and the height of the controller and then we click on ' Start base station'.
4
• According to AOI (Area Of interest), surveyor go to the point approximately 1 km from the base station and mark the static point by using Rower .
5
• Now surveyor placed the point for 10- 15 min (Time is according to the range of base station). The more surveyor go far from the base station, the time for placing the static point will be more.
6
• Surveyor placed the point for 10- 15 min (Time is according to the range of base station). The more surveyor go far from the base station, the time of placing the static point will be more.
7
• If the surveyor wants to go beyond the range of the base station, he must place the base station where he take static point and the survey (i.e shown in pictorial diagram).This method is called Leap frog Method.
Communication link for position
correction
Satellite Constellation
Reference Station (Fixed receiver,
Known Position)
Remote Station (Roving Receiver)
Distribution of the GCPs collected over the area.
GCP ID X Y Z
GCP60 327666.1 2951066 67.93
GCP61 325515.5 2949895 68.31
GCP62 325534.6 2951983 68.18
GCP46 328622 2954757 70.48
GCP47 327374.9 2954059 68.69
GCP17 324858.1 2957267 71.04
GCP18 327749.4 2955279 69.39
GCP19 328448.9 2957427 69.71
GCP20 327828.3 2958858 72.2
GCP21 330743.4 2959368 72.67
GCP48 330737.2 2958314 74.75
GCP49 332303.6 2957964 76.09
GCP51 328445.8 2957327 70.6
GCPs with their IDs and corresponding values (in meter).
GCP 18 GCP 19
GCP 17
Few pictures of surveyors collecting GCPs
Aerial Triangulation
Aerial Triangulation (AT) represents the mathematical process of establishing precise and
accurate relationships between the individual image coordinate systems and a defined datum
and projection (ground).
The main objective of aerial triangulation is to produce from ground control, sufficient points
in the photogrammetric models to ensure that each model can be oriented accurately as
required for stereo compilation in either orthophoto or line mapping.
There are mainly three stages of aerial triangulation:
Preparation
• Point identification of ground control
• Numbering settings for points, images and strips
• Input data: flight details (photo coordinates plus omega, phi and kappa rotation), camera
calibration and scanned or digital images
Image Measurement
• Interior orientation (fiducial marks measurement for analogue cameras)
• Automatic tie points determination using images pyramid levels
• Ground control points measurement
• Manual tie points measurement if necessary (in cases where automatic measurement
could not determine an acceptable number of tie points per image or in failure situations)
Block Adjustment
• Input of observations (x, y, z coordinates or GPS/IMU, ground control) and initial
parameter values.
• Preliminary data processing, including generation of initial values for bundle adjustment
parameters.
• Iterative solution (including specials algorithms for determination of blunders and error
propagation).
• Acceptance of results (after accuracy and reliability assessment).
• Final output of results (EO data).
Aerial Triangulation workflow
Photogrammetry engineer at SATPALDA performing Aerial Triangulation